Friction hinges are used for positioning display screens in lap-computers, medical equipment and video monitors in automobiles as well as many other applications. A commonly used method for making friction hinges utilizes a single turn of a wide spring material tightly fitted over a round shaft. One attachment to this type of hinge is made to the shaft, and the other is made to the tail, or end, of the flat spring material which extends tangentially from the circular wrap about the shaft.
This method is inexpensive and capable of providing good performance and reasonably long life. But it has the disadvantage that the tail of the flat spring material flexes under bending loads as the display is moved from one position to another. Such bending makes it difficult for the user to position the display accurately.
One prior art method for reinforcing the flat portion of the band consists in forming ridges or bending ribs into the band during forming. These methods do stiffen the band, but they make it much more difficult to form the band accurately, with the result that the frictional characteristics of the hinge are not as controllable.
Another method for stiffening the band uses a separate rib, perpendicular to the band, and attached to the flat portion of the band along one of its edges. The prior art includes an attachment method consisting of tabs formed as a part of the band which engage slots in the reinforcing rib. Failures of this method occur when the reinforcing rib moves so as to lose its engagement with the tab of the band.
Accordingly, it would be desirable to provide a method for ensuring permanent and firm attachment of the reinforcing rib to the edge of the band without incurring significant extra cost in tooling, material, or assembly labor.